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Platesetter Inspector

a video presentation by David Hunter

 

Track Plate consistency with ChromaChecker™ Plate Inspector.

Our procedure makes it fast and easy to quality control your plates with ChromaChecker Plate Inspector. 

ChromaChecker provides three different targets to enable tracking your plates and platesetters in three different ways. You don't need to use all three, for many people, one method may be enough. The three targets provide the ability to assess the plate and platesetter in three conditions, most users will only need option 1 or option 1 and 2.
1) Plate imaged in linearized condition (Dot Inspector D,E or L targets)
2) Plate imaged in it's tone curve (G7 or dot gain compensated) condition (Dot Inspector C target).
3) Plate imaged in raw (naked) condition, no linearization, no tone curve applied (Dot Inspector R target)- this scenario is more complicated and covered in further detail below.

Control Strips

In the non-printed area (Example 1):

  • One linearization control strip (Dot Inspector D, E or L) should be placed in non-press-compensation-area (no Dot Gain/TVI curves applied) – this control strip enables daily plate-setter linearization verification.




  • One DotGain control strip (C) should be place within press compensation area (Dot Gain/TVI applied) that will enable the operator to measure current press compensation curves (G7 or TVI calibration)


Barcodes

To minimize mistakes ChromaChecker Best Practices strongly recommends using barcodes to identify various variables in the workflow. Three different bar codes will quickly identify 1) Proper plate condition (line screen/type) 2) Job number, 3) Scanning template, which plate (CMYK) and condition

1) Bar code #1 identifies: Plate-Setter Settings (Conditions)— If you are using more than one setting on your plate-setter (various screen rulings, dot shape or screen types - or if you have more than one plate-setter it becomes critical to properly identify these different variables to ensure the plate is imaging with the correct variables. You will want to create a barcode that corresponds to each of your plate conditions and register each condition in ChromaChecker Plate Inspector.

2) Bar code #2 identifies: Job Identification— On your Platesetter RIP set Job Id to be imaged as a barcode (use code39 font) - this feature is very helpful for not only plates but all print inspector measurements. Job ID (in most cases created by MIS) can be entered with a barcode scanner to properly recognize each job.  

3) Bar code #3 identifies: Scanning template- Using ChromaChecker Dot Inspector control strips that contain barcodes that will identify the plate condition and job number for the given plate within the quality measurement software.

 

Barcode coding convention.

In order to use barcodes an auto-barcode-recognition specific convention has to be respected.
Note that Code39 uses "*" for both start and stop delimiters.

1. Plate setter conditions/settings - use barcode specified in Plate Inspector that corresponds to selected plate setter condition. If required an alias can be defined - especially if custom names are preferred. Note that the barcode for plate setter condition always start with prefix: “/“

2. Job ID barcode - Configure to your system Job ID (use supported characters only) requires prefix: "*"

Example 1:

 

will be reported as Job ID=  JS-325-557-LTT

All three stars will be ignored, but they are required to properly interpret barcode.

 

3. Scanning Template contains prefix "#" and two characters:

  • First stands for control strip type e.g. C, D, E, L
  • The second one defines ink color: C, M, Y, K

An example:

Means: Dot Inspector D control strip / black plate
 

Measurements

You may use one of plate readers (slower, but more precisely) or spectrophotometer (faster, but less accurate)

 

 

ChromaChecker InstrumentDrive software is planned to be publicly available in March 2018. 

 

Measuring Plate in raw condition- possible enhancement - create Dot Inspector R control strip

Advanced users may create an additional control strip Dot Inspector R. It is a bitmap version created from system TIFF-B - rasterized by the RIPs current setting from Dot Inspector D, E or L. To create proper TIFF-B plate setter operator has to turn off both linearization and press-calibration curves. RIP will rasterize all vector patches to 1-bit using exactly same screening technology that is used during production. As a bitmap, this control strip will be not processed — and will represent plate's raw state. By measuring this control strip the operator can fix plate linearization curve from any production plate. 

Plate with 3 Control Strips (advanced mode)

Advanced users will be able to measure one of three targets on each plate which tracks:

  1. Raw plate baseline condition (non-linearized, without press-calibration compensation) — determines if the mechanics of plate and plate setter are consistent, fast correction of plate linearization [black]
  2. Linearized plate — quality control (checker test brings enhanced reporting)— determines if platesetter's linearization is accurate. [red]
  3. Tone reproduction curve with press-calibration compensation — includes current G7 or TVI press calibration curves— determines if the press tone reproduction curve is correctly applied to plate. [blue]

Most plates are big enough to place multiple control strips - it is a good idea to repeat Dot Inspector R two or more times to be able to check plate uniformity - we recommend to check left -center -right uniformity at least once per month. With spectrophotometer, this is very fast. This assessment will uncover hardware errors with this simple procedure.

 

Procedures

A. Plate verification – daily routine for randomly selected plate

  1. Select proper Plate Setter Condition or scan barcode (nr.1 on the picture above)
  2. Enter Job ID or scan barcode (nr.2)
  3. Select scanning template/ plate color or scan Scanning Template barcode
  4. Measure Control strip
  5. If fails re-linearize plate setter.

 

B. Check your current press-compensation curves (G7 or TVI calibration curves)

  1. Select proper Plate Setter condition or scan barcode (nr.1 on the picture above)
  2. Enter Job ID or scan barcode (nr.2)
  3. Select scanning template/ plate color or scan Scanning Template barcode for Dot Inspector D, E or L 
  4. Measure Control strip
  5. Select scanning template/ plate color or scan Scanning Template barcode for Dot Inspector C
  6. Measure Control strip Dot Inspector C
  7. Repeat procedure to complete measurements for all colors (e.g. C, M, Y,  K)
  8. If necessary rename measured curves 

Measured curves can be used as initial curves whenever you are performing calibration from production. Both G7 and TVI calibration method — Curve Inspectors requires initial curves to enter. Whenever the operator is not sure how to read them from the RIP he can confirm it by this kind of measurement. 

Software calculation will extract press-calibration – even if linearization is not correct (both input and output values will come from measurements. Thanks to such methodology error is small - using spectrophotometer for this purpose instead of plate reader will bring good results (both curves have to be measured with the same instrument) 

 

C. Re-linearize plates

  1. Read Dot Inspector R from at least 3 sets of production plates. 
  2. Average measurements and enter linearization values to the RIP 

  

D. Check Plate uniformity

For monthly verification read 3-4 Dot Inspector R from a randomly selected plate. If the test fails – perform full audit procedure.

 

 

 

Download Dot Inspector control strips

To download  CMYKOGV zip file — click here

To download CMYK zip file — click here.

 

 

 

 

Plate Setter Audits

Consult Dot Inspector Manual to learn more how to make an audit of your Platesetter (or Imagesetter).